Conventionally, as a hose, which is connected to a piping equipment, such as a pressure regulator and a fuel strainer of a car, or a hose, such as fuel hose of a car engine, which is mounted to a car, an elastic hose wholly made of rubber or an elastic hose having a rubber layer in at least its one portion has been usually used. Moreover, it is desired that such elastic hoses do not require removing in use for maintenance after being connected to a piping equipment, namely, a maintenance-free elastic hose is desired. For this reason, such an elastic hose has a tendency to be connected so that it cannot be removed by an usual method.
Further, recently, in order to attempt to reduce cost, a resin hose is used instead of a conventional rubber hose and a hose having a rubber layer, However, since the resin hose does not have sufficient elasticity compared with the rubber hose, it has an disadvantage such as insufficient sealing on a connecting portion with a cylindrical member. Moreover, in order to provide a maintenance-free resin hose, it is necessary to securely connect the resin hose to the cylindrical member so that they cannot be removed. However, since permanent set in fatigue is liable to occur in the resin hose, there arises another problem from this point of view.
Therefore, conventionally, a coupling unit intervenes between an elastic hose, such as a fuel hose and a piping equipment, such as a pressure regulator and a fuel strainer, and the hose is stuck to the one end of the coupling unit so as that they cannot be removed. For example, as shown in FIG. 1, an inserting section 31 of connecting fittings 30, such as a flare coupling, is inserted into one end 11 of an elastic hose 10, and they are previously cramped by a fastener, such as a sleeve 35 and secured so that they cannot be removed each other in a hose manufacturing factory, Thereafter, a nut-like coupling section 32 on the opposite side to the insert section 31 of the connecting fittings 30 is connected to a metallic pipe 20, such as a fuel strainer, and secured by a sleeve-like clamp screw 33 or the like in an auto assembly plant. Here, 12 in the drawing is a reinforcing layer composing a reinforcing system.
In addition, in recent years, the complicated coupling unit mentioned above is not used, but a connecting coupling, such as a quick connector, which can be easily connected to a tubular member for connecting hose with one step, is frequently used. Furthermore, there is a great demand for a reduction in cost recently and thus it is unavoidable to decrease a number of parts. Therefore, in the case where a hose is connected to an equipment, it is attempted to directly connect the elastic hose, such as the fuel hose, to a metallic pipe or the like provided to a piping equipment, such as a fuel strainer, without intervention of a coupling unit.
For example, as shown in FIG. 2, one end 11 of an elastic hose 10 is directly inserted into an inserting section 21 of a metallic pipe 20 provided to a piping equipment, such as a fuel strainer mounted to a car, and various fasteners, such as a clip 42 is installed to the outer circumference of the one end 11 of the elastic hose 10 so that the elastic hose 10 closely secured to the metallic pipe 20, etc. and secured, As the fastener, besides the clip 42 shown in the drawing whose zonal elastic body is formed so as to have a ring shape and which fastens the elastic hose 10 securely by utilizing elastic force due to decrease in a diameter, and a band or the like for fastening both the ends of a fastening member by means of securing means, such as a bolt and a nut and decreasing a diameter is known. 22 in the drawing is a ring convex portion provided to the circumferential surface of the inserting section 21 of the metallic pipe 20 for preventing the hose from coming off.
These conventional methods use the fastener, but when the fastener is used for a long time, the hose is deteriorated due to heat, and thus securing force of the end of the elastic hose fastened by the fastener is decreased. As a result, the fastener does not suitably work, and thus sealing might be lowered. Moreover, the use of the fastener might cause a notch, a crack, etc. on the ends of the elastic hose to which the fastener is attached.
Meanwhile, Japanese Unexamined Utility Model Publication No. 61-96075/1986 (Jitsukaisho 61-96075) discloses a hose terminal protection cap made of an elastomer material of a ring cylinder with bottom, which surrounds an end face and outer and inner face of a hose terminal. This hose terminal protection cap is inserted into the hose terminal so that a notch and a crack is caused in the hose when the hose connected to a pipe or the like is fastened by a fastener. However, the protection cap is a molded product, which is separately produced from the hose, it is thick and is not fastened to the hose, so it is liable to remove from the hose terminal.
In addition, Japanese unexamined Utility Model Publication No. 57-25292/1982 (Jitsukaisho 57-25292) discloses a metallic piping coupling whose outer surface of a connecting portion is coated with silicone rubber or fluororubber and which is connected to a flexible tube. However, when the coupling is pressed into a hose terminal, a ring convex portion on an outer circumference of the coupling is rubbed with an inner circumference of the hose until the end of the insertion, and thus a coating layer of the ring convex portion is partially worn out, so sealing properties between the hose and the coupling are liable to damage. Moreover, since the ring convex portion is on the outer circumference of the coupling, it is difficult to apply a coating layer uniformly to the coupling, and particularly the top part of the ring convex portion is liable to be thin. For this reason, the sealing properties are further lowered, and the sealing properties are not constant, so quality control becomes difficult.
Furthermore, in the connecting structure of the piping coupling and the hose, in the case where the sealing properties are damaged in use, the original sealing properties cannot be maintained without replacement of both the hose and the piping coupling. This is because since securing force of the hose is lowered due to plastic deformation in pressing the hose into the coupling and to thermal degradation in using the hose, when the hose is reused, it does not have its original repulsion force, and thus the hose and the coupling do not come closely into contact. On the other hand, when the coating layer formed on the outer circumference of the coupling is once used by connecting it to the hose, it is stuck to the hose due to heat and a secular change, and it is not easy to completely remove the coating layer.